Express middleware to validate requests based on an OpenAPI 3.0 document. OpenAPI specification was called the Swagger specification before version 3.
Install this package with npm or yarn:
npm install --save express-openapi-validate
# or
yarn add express-openapi-validateThen use the validator like this:
const fs = require("fs");
const express = require("express");
const { OpenApiValidator } = require("express-openapi-validate");
const jsYaml = require("js-yaml");
const app = express();
app.use(express.json());
const openApiDocument = jsYaml.safeLoad(
fs.readFileSync("openapi.yaml", "utf-8"),
);
const validator = new OpenApiValidator(openApiDocument);
app.post("/echo", validator.validate("post", "/echo"), (req, res, next) => {
res.json({ output: req.body.input });
});
app.use((err, req, res, next) => {
const statusCode = err.statusCode || 500;
res.status(statusCode).json({
error: {
name: err.name,
message: err.message,
data: err.data,
},
});
});
const server = app.listen(3000, () => {
console.log("Listening on", server.address());
});Or using match():
// Apply to all requests
app.use(validator.match());
// On each request validator.validate("post", "/echo") is called automatically,
// if it has a matching specification in the OpenAPI schema
app.post("/echo", (req, res, next) => {
res.json({ output: req.body.input });
});openapi: 3.0.1
info:
title: Example API with a single echo endpoint
version: 1.0.0
components:
schemas:
Error:
type: object
properties:
error:
type: object
properties:
name:
type: string
message:
type: string
data:
type: array
items:
type: object
required:
- name
- message
required:
- error
responses:
error:
description: Default error response with error object
content:
application/json:
schema:
$ref: "#/components/schemas/Error"
paths:
/echo:
post:
description: Echo input back
requestBody:
content:
application/json:
schema:
type: object
properties:
input:
type: string
required:
- input
responses:
"200":
description: Echoed input
content:
application/json:
schema:
type: object
properties:
output:
type: string
default:
$ref: "#/components/responses/error"- Validating request bodies with a schema (See Request Body
Object and Schema
Object)
- All schema properties in a Schema Object that are directly supported by JSON Schema and Ajv are used in validation
- Schemas are validated according to JSON Schema Specification Wright Draft 00 (draft-04/05) as specified in OpenAPI specification
nullablefield for handling properties that can be null is supported (See OpenAPI fixed fields)- Validation according to
formatincluding additional data type formats (like int32 and bytes) defined by OpenAPI (See OpenAPI data types and Ajv formats)
- Validating parameters: query, header, path and cookies (including signed
cookies) (See Parameter Object)
- The same
schemafeatures that are supported for request bodies are also supported for parameters requiredfield for marking parameters that must be given is supported
- The same
- Validating response bodies and headers in tests (See Responses Object and Header Object)
- References to Components Object (See Reference Object)
- Typescript definitions are included in the package
- Discriminator keyword
- Validating request bodies with media type other than
application/json(Seecontentunder Request Body Object) - Some OpenAPI Schema Object specific fields are
unsupported:
deprecatedxml
- External references (references to other files and network resources) (See Reference Object)
- Parameter Objects (including Header
Objects) that define shape using
contentandstyle(onlyschemais supported) - Links and callbacks (See Callback Object and Link Object)
- Encodings (See Encoding Object)
const { OpenApiValidator } = require("express-openapi-validate");The main class of this package. Creates JSON schema validators for the given operations defined in the OpenAPI document. In the background Ajv is used to validate the request.
Creates a new validator for the given OpenAPI document.
options parameter is optional. It has the following optional fields:
{
ajvOptions: Ajv.Options;
}You can find the list of options accepted by Ajv from its
documentation. The formats object passed to Ajv will be merged
with additional OpenAPI formats supported by this library.
Returns an express middleware function for the given operation. The operation matching the given method and path has to be defined in the OpenAPI document or this method throws.
The middleware validates the incoming request according to the parameters and
requestBody fields defined in the Operation
Object. If the validation fails the next express
function is called with an
ValidationError.
See the Parameter Object and Request Body Object sections of the OpenAPI specification for details how to define schemas for operations.
method must be one of the valid operations of an OpenAPI Path Item
Object:
"get" | "put" | "post" | "delete" | "options" | "head" | "patch" | "trace".
RequestHandler is an express middleware function with the signature
(req: Request, res: Response, next: NextFunction): any;.
Returns an express middleware function which calls validate() based on the
request method and path. Using this function removes the need to specify
validate() middleware for each express endpoint individually.
match() throws an error if matching route specification is not found. This
ensures all requests are validated.
Use match({ allowNoMatch: true}) if you want to skip validation for routes
that are not mentioned in the OpenAPI schema. Use with caution: It allows
requests to be handled without any validation.
The following examples achieve the same result:
// Using validate()
app.post("/echo", validator.validate("post", "/echo"), (req, res, next) => {
res.json({ output: req.body.input });
});
// Using match()
app.use(validator.match());
app.post("/echo", (req, res, next) => {
res.json({ output: req.body.input });
});Creates a function for the given operation that can be used to validate responses. Response validation is meant to be used in tests and not in production code. See below for example usage.
For documentation of the method and path parameters see
validate.
res is expected to have the shape
{ statusCode: number, body: {}, headers: {}}. The statusCode field can also
be called status and the body field can be called data. This means that
response objects from most request libraries should work out of the box.
If validation fails the validation function throws a
ValidationError. Otherwise it returns
undefined.
Example usage when using Jest and SuperTest:
import { OpenApiValidator } from "express-openapi-validate";
import fs from "fs";
import jsYaml from "js-yaml";
import request from "supertest";
import app from "./app";
const openApiDocument = jsYaml.safeLoad(
fs.readFileSync("openapi.yaml", "utf-8"),
);
const validator = new OpenApiValidator(openApiDocument);
test("/echo responses", async () => {
const validateResponse = validator.validateResponse("post", "/echo");
let res = await request(app).post("/echo").send({});
expect(validateResponse(res)).toBeUndefined();
res = await request(app).post("/echo").send({ input: "Hello!" });
expect(validateResponse(res)).toBeUndefined();
});const { ValidationError } = require("express-openapi-validate");This error is thrown by OpenApiValidator#validate when the request validation
fails. It contains useful information about why the validation failed in
human-readable format in the .message field and in machine-readable format in
the .data array.
You can catch this error in your express error handler and handle it specially. You probably want to log the validation error and pass the errors to the client.
Human-readable error message about why the validation failed.
This field is always set to 400. You can check this field in your express
error handler to decide what status code to send to the client when errors
happen.
Machine-readable array of validation errors. Ajv Error
Objects documentation contains a list of the fields in
ErrorObject.
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